Superoxide dismutase: A comparison of rate constants

摘要: O2−was introduced, at a constant rate, into buffered aqueous solutions, either by mechanical infusion of KO2, dissolved in tetrahydrofuran, or the situ action xanthine oxidase on plus oxygen. This O2− was allowed to react with ferricytochrome c tetranitromethane and formation reaction products, ferrocytochrome nitroform, respectively, monitored spectrophotometrically. That concentration Superoxide dismutase, which competed equally given levels cytochrome thus caused 50% inhibition rates accumulation determined. The rate for enzymatic dismutation copper zinc containing enzyme from bovine erythrocytes then calculated known constants found be 2 × 109m−1 sec−1 pH 7.8 8.5. obtained steady-state concentrations 10−8m → 10−13m range is full agreement results pulse radiolytic investigations were performed 10−5m range. second order independent 10−5 10−13m. Several distinct types dismutase have been described. These include mangano-enzymes Escherichia coli chicken liver mitochondria iron-enzyme E. coli. dismutations catalyzed these enzymes also investigated as function pH.